1. Field of the Invention
This invention relates to a unit for deciding the coloration of a test piece by comparison with reference samples. Such a unit is typically used for biochemical tests (such as a urine sugar test, a blood sugar test, or a urobilin test) and is hereinafter referred to as "a test piece coloration comparative decision unit", when applicable. More particularly, the invention relates to a test piece coloration comparative decision unit which is used for making a decision concerning the coloration of a test sheet (reagent part) impregnated, for instance, with urine which test sheet is then compared with a plurality of reference sample colors in order to determine sugar content in the urine.
2. Discussion of the Prior Art
Heretofore, in a biochemical test for urine or the like, the coloration of a test sheet is determined by a non-electronic color comparative decision system in which an operator visually reads the coloration of the test sheet, or with an electronic urine sugar meter (an electronic biochemical measuring instrument) which comprises, for example a reflection sensor, for automatically reading and displaying the result of a test sheet coloration.
FIG. 4 is a perspective view showing a conventional non-electronic test piece coloration comparative decision unit. It comprises: a cylindrical case 72 with a cap 71; and a sheet-shaped comparing color sample part 73 bonded to the cylindrical outer wall of the case 72. A number of test sticks (each comprising a resin sheet, and a test sheet 75 impregnated with a reagent and bonded to one end of the resin sheet) 74 are accommodated in the cylindrical case 72. In a urine sugar test, the cap 71 is removed from the cylindrical case 72, and a test stick 74 is taken out of the case 72. Then, the test sheet 75 is impregnated with urine. Upon impregnation with urine, the test sheet 75 shows a color reaction according to the content of sugar in the urine. The color of the test sheet 75 thus treated is compared with various colors provided in the comparing color sample part 73 on the cylindrical case 72, for the purpose of deciding the coloration of the test sheet. That is, in the color sample part 73, various color samples (for negative and positive signs) 73a provided separately according to the content of sugar (grape sugar) in urine are arranged in a plurality of lines. The color of the test sheet 75 thus treated is compared with the variety of colors 73a in the color sample part 73 in order to find the same color (or a color substantially similar thereto), whereby the coloration is determined. More specifically, it is determined whether the content of sugar in the urine is more or less than a standard (or negative or positive).
In an electronic biochemical measuring device, such as a urine sugar meter, a reflection sensor is used which includes a light emitting element and a light receiving element. In this device, light is applied to the coloration test sheet by the light emitting element (such as a light emitting diode), and light reflected from the test sheet is received by the light receiving element (such as a photo-transistor), so that the urine sugar value is automatically displayed in a digital mode according to the received color reaction light quantity.
The first described, non-electronic, test piece coloration comparative decision unit is formed merely by bonding the sheet-shaped color sample part to the outer cylindrical wall of the test stick accommodating case (i.e., the cylindrical case). Therefore, for a color comparison, the test stick impregnated with the urine is held with the fingers and placed successively beside the various colors in the color sample part until the same color as the test sheet or a color similar that of the test sheet is found. That is, in the color comparison, the operator must incrementally move in fine steps the test sheet impregnated with the urine, i.e., the used test sheet, along the color sample part with a very small gap between the color sample part and the test sheet which requires considerable dexterity. Furthermore, in the color comparison, the test sheet is liable to shift from the color sample, and therefore it can be difficult for an operator to accurately decide the delicate color difference between various colors of the color sample part.
In the electronic biochemical measuring unit (such as a urine sugar meter) the reflection sensor receives the color reaction light quantity of the test sheet, and the sugar value is automatically displayed according to the color reaction light quantity thus received. Therefore, with this device, the labor and time required for operation of the coloration comparative decision unit, and the operation of referring a mean value (urine sugar value) of a selected color to a comparison table to decide a color value (or a negative sign or positive sign) can be eliminated. However, the electronic biochemical measuring unit is disadvantageous in that, since it employs a reflection sensor, it is expensive, and is also sometimes difficult to accurately detect the delicate coloration of the test sheet with this device.